The present invention relates to a developing device and an image forming apparatus.
A conventional image forming apparatus of an electro-photography type such as a printer, a copier, a facsimile, and a multi-functional device includes a photosensitive drum (image supporting member); a charge unit having a charge roller for charging a surface of the photosensitive drum; an exposure device for exposing the surface of the photosensitive drum to form a static latent image or a latent image thereon; a developing roller for attaching toner to the static latent image on the photosensitive drum to form a toner image thereon; and a transfer unit for transferring the toner image to a recording medium; and a fixing unit for applying pressure and heat to toner transferred to the recording medium at the transfer unit for fixing, thereby recording or printing an image on the recording medium.
In a certain type of image forming apparatus, a developing device is integrally formed of a photosensitive drum, a charge unit, and a developing roller.
FIG. 2 is a perspective view of a major portion of the conventional developing device. FIG. 3 is an enlarged view of the major portion of the conventional developing device.
The developing device (image forming processing cartridge) is detachably attached to a main body of a printer and extends in a direction perpendicular to a direction of transporting a sheet (not shown). Four developing devices are disposed in a row along the sheet transporting direction, and compose image forming units of black, yellow, magenta, and cyan. Each of the developing devices comprises a main body of the developing device and a toner cartridge detachably attached to the main body of the developing device for holding toner in each color.
The developing device has a base frame 14 and an upper frame (not shown). The based frame 14 supports a photosensitive drum (image supporting member), a charging roller, a developing roller, a cleaning member, and so on. A film 23 is attached onto a bottom surface of the base frame 14, and a supply roller assembly 61 having a supply roller 18, a stir bar 26, and so on is attached to a side surface of the base frame 14.
The supply roller assembly 61 has sealing members 39L and 39R at both ends thereof for supporting the supply roller 18 and the stir bar 26, and sealing plates 28L and 28R for holding the sealing members 39L and 39R (only sealing plate 28R is shown in FIG. 2). Each of the sealing members 39L and 39R has a side sponge 29 arranged to contact with an end surface of the supply roller 18 and a felt sponge 30 arranged to contact with an outer circumferential surface of the developing roller at an end thereof. (For example, see Patent Reference)
Patent Reference: Japan Patent Publication No. 2002-108089
In the conventional image forming apparatus described above, it is difficult to seal the supply roller assembly 61 with a sufficient force. Accordingly, when the developing device is attached to a main body of an image forming apparatus, toner (not shown) may be leaked from the both ends of the supply roller assembly 61.
In view of the problem described above, an object of the invention is to provide a developing device and an image forming device, in which it is possible to solve the problems of the conventional printer and improve sealing.
Further objects of the invention will be apparent from the following description of the invention.